pererr=.2;
xoff=.0005/2;

for i=1:length(S2O3s)
X=S2O3s(i);
Y=Sts(i,1);
err=pererr*Y;

line([X X],[Y-err,Y+err],'Color','k');
line([X-xoff X+xoff], [Y+err Y+err],'Color','k');
line([X-xoff X+xoff], [Y-err Y-err],'Color','k');
end